I'm setting up an external drive to boot a 2017 iMac with failing internal Fusion drive. It boots fine from an external OWC Envoy Pro EX (too small for this application) but with a SanDisk G-Drive Pro I get a question mark and need to hold Option when I power it. Then the drive is recognized and it boots in seconds.
Why is the SanDisk treated different from the OWC?
iMac
Does the same behaviour occur when booting via Safe Mode
If Yes, then it would appear the user will have to live with the Option key method.
CSU_FMA wrote:
I'm setting up an external drive to boot a 2017 iMac with failing internal Fusion drive.
It boots fine from an external OWC Envoy Pro EX (too small for this application) but
with a SanDisk G-Drive Pro I get a question mark and need to hold Option when I power it. Then the drive is recognized and it boots in seconds.
Why is the SanDisk treated different from the OWC?
?
external boot you would expect to hold the Option key to see the StartUp Disk Manager—
Change your Mac startup disk - Apple Support
Mac startup key combinations - Apple Support
Mac models with the Apple T2 Security Chip - Apple Support
About Startup Security Utility on a Mac with the Apple T2 Security Chip - Apple Support
Has the SanDisk every been bootable without going thru the Option?
Have you tried the SanDisk on another Mac?
By too small do yo mean there's not enough storage space for the files you'll be using? If so can't you run them from another external drive while booting into the OWC drive?
Same issue when trying to boot into Safe Mode.
This is a lab computer, so it will see lots of users. Could the fact that this is a managed device make a difference? Logic says not, since it works as desired with the OWC.
The SanDisk has never booted seamlessly on this iMac, but does boot seamlessly on a Macbook Pro. (It was created using the Macbook this morning.) The OWC, also created on the Macbook a month or so ago, boots seamlessly on both. I used it to troubleshoot the iMac's failing internal drive.
We have the OWCs on several 21" iMacs that run excruciatingly slow on their internal drives. They are only 250GB, but that is big enough for their usage. This iMac will be used in a film school lab with Adobe CC, Media Composer, Resolve, ProTools, Office and other applications. All media should be stored on the networked media server, but students do not always do as instructed. The SanDisk is a smaller package but 4 time larger than the OWC. I don't want two drives hang off this lab computer.
I have set the Start Up drive to the SanDisk. It is named Macintosh HD. This iMac boots directly to the OWC with no intervention. It is only the SanDisk that requires Option.
How may Other External Drives are attached at the Cold Boot Up using the Problematic Drive ?
This is the only external drive connected. It will boot from the OWC seamlessly, but the SanDisk, only via Option.
The SanDisk boots seamlessly on a Macbook, however.
Sorry, out of my Skill Set to answer.
Perhaps @leroydouglas has more insights
External Start Up drive not recognized unless I hold Option when I power up
